Introduction

Prior single-institution retrospective studies suggest that age may independently predict risk of Gleason progression on repeat biopsy following a diagnosis of low risk prostate cancer (PCa). Older men experience higher rates of PCa-specific mortality; therefore, the appropriateness of active surveillance may differ in an older patient population and is influenced by the probability of undersampling for occult higher grade disease. Furthermore, the clinicopathologic features most useful in guiding decisions to re-biopsy remain poorly defined. We therefore sought to investigate the risk of Gleason upgrading on repeat biopsy, as well as the features most suggestive of potential Gleason misclassification.

Methods

We retrospectively reviewed charts of 635 men on active surveillance at our institution between 2002 to 2015. Demographic and clinicopathologic features including age, race, initial PSA, prostate volume, clinical staging, and biopsy findings were collected. Within this population, we identified 556 men who were diagnosed with Gleason 3+3 disease on initial biopsy, of whom 406 received a documented confirmatory biopsy within 1 year of diagnosis. Logistic regression modeling was performed to determine features associated with detection of Gleason 7 or higher disease on confirmatory biopsy.

Results

Eighty-five of 406 patients (21%) with initial Gleason 6 disease who received a repeat confirmatory biopsy were found to have grade reclassification. On multivariable analysis, older age (per year OR 1.07; 95% CI 1.02-1.11; p = 0.003) and number of positive cores (per core, OR 1.38, 95% CI 1.10-1.73; p = 0.05) were significantly associated with reclassification on confirmatory biopsy (Table 1). Initial prostate volume, clinical stage, and PSA were not found to be associated with this risk.

Conclusions

Older age and the number of positive cores on diagnostic biopsy appear to predict for risk of misclassification of Gleason 7 or greater disease. Therefore, in this setting, a repeat biopsy may be particularly warranted to minimize the chances of diagnostic misclassification.

Funding

None